Re: [Libguestfs] [PATCH libnbd v3] python: Raise a custom exception containing error string and errno.

On 6/28/19 2:17 PM, Richard W.M. Jones wrote: Yeah, avoiding the segfault is still worthwhile - but our lack of PyFOO_BAR() error checking is more pervasive than just in raise_exception(), so a patch to audit all of our generated code will pick that up along with the rest. Maybe we want two fields, both .errno (string name, or None if Python errno.errorcode couldn't map it to a name), and .errnum (raw numeric value, accessible no matter what). Maybe as simple as this (or with one further tweak to __str__ to at least output .errnum when .errno is None): diff --git i/generator/generator w/generator/generator index 7c2fb59..9192988 100755 --- i/generator/generator +++ w/generator/generator @@ -3944,11 +3944,14 @@ from libnbdmod import Error Error.__doc__ = ''' Exception thrown when the underlying libnbd call fails. -This exception has two properties to query the error. Use +This exception has three properties to query the error. Use the .string property to return a printable string containing -the error message. Use the .errno property to return a -Python errno (which may be None in some cases if the error -did not correspond to a system call failure). +the error message. Use the .errnum property for the associated +numeric error value (which may be 0 if the error did not +correspond to a system call failure), or the .errno property to +return a string containing the Python errno name if one is known +(which may be None if the numeric value does not correspond to +a known errno name). ''' Error.string = property (lambda self: self.args[0]) @@ -3961,6 +3964,8 @@ def _errno (self): return None Error.errno = property (_errno) +Error.errnum = property (lambda self: self.args[1]) + def _str (self): if self.errno: return (\"%%s (%%s)\" %% (self.string, self.errno)) -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org